I know I might have had a couple of typos on my blog. Please forgive me. It doesn't bother me if I see one on someone else's blog. I'll keep coming back. But on a professional website I'm much more critical. If I see a typo on that, I don't take it seriously.
Typos on Twitter or Facebook don't bother me at all, but I consider a blog post equal to an article and find typos, incorrect grammar or syntax errors unacceptable.
If you want to write, do it right. Invest in
Strunk and White's "The Elements of Style" and "The Chicago Manual of Style" and give the written word appropriate respect.
If they are honest mistakes, I don't mind. What bothers me the most is when the wrong spelling for a word is used (i.e. there and their) homonyms. I feel that if your old enough to have a blog, your old enough to know the difference between words that sound the same but are spelt different. That is the only real irk I have with spelling, unless there are a lot of typos, then that kinda bugs me too.
I realize fingers tend to work faster then your brain sometimes, but there is always spell check and backspace keys.
Typos are okay. Everyone makes mistakes. But bad grammar, sometimes that gets me, mostly because it breaks my concentration and I have to think about what they are trying to say. But generally, I'll go back if I like the content.